The other morning after my truck sat for two hours, every time I put it in reverse or drive it would stall. I had to drive home using both feet. I got it towed to the dealer and OF COURSE IT WAS FINE, when thay had it. They did not fix anything and it cost me $80 for diag charge, which I was not to happy, because the engine never came on. HELP?

your problem is the IAC valve on top of the intake manifold !
this control valve is notoriously responsible for stalled engines due to low idle rpm or no idle at all.
unfortunatle you have already shelled out a few bucks to find that it is not monitored by the computer and therefor will not show up during diagnostic tests.
it will not trigger an engine light either.
around here they cost about $65.
they have two 8 mm bolts holding them on and anyone can replace one just unplug and replace.

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i would rather push my Ford than drive your Chevy !

I had the same problem with my 99 sport. My machanic changed the TPS and the AIS. It helped but didn't completely fix the problem. He couldn't get anything to show on his diagnostic machine. He called his buddy that works at the dealership and he looked it up in the troubleshooting database.

It is caused by a buildup of carbon in the throttle body. The guy says that all the cases listed were from 99's. You have to soak in a specified cleaner. My guy had to do it twice because it was so bad. And possibly replace a gasket if you damage it removing it. Total fix was ten bucks (not counting labor).

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